Metal composition and bearing



fi e a OF? PQRQBUBO Patented Jan. 29, 1946 M'ETAL COMPOSITION ANDBEARING Franz R. Reuse] and Earl I. Larsen, Indianapolis,

Ind., assignors to P. R. Mallory & 00., Inc., Indianapolis, Ind., acorporation of Delaware No Drawing. Application September 4, 1943,Serial No. 501,292

3 Claims.

This invention relates to sintered copper base metal compositions, andbearings made therefrom.

An object of the invention is to improve copper base metal compositionsand bearings.

This application is a continuation in part of our co-pending applicationSerial No. 333,928, filed May 8, 1940, now matured into Patent No.2,372,202, issued March 27, 1945.

Other objects of the invention will be apparent from the description andclaims.

Sintered metal compositions present a number of advantages over cast andwrought materials for several applications. The metal powders can bemolded into intricate shapes and the high cost of machining reduced oreliminated. They also afford better bearing properties than castmaterials. Where some porosity is allowed to remain they can beimpregnated with a lubricant metal or oil. Also lubricant materials suchas lead or graphite can be incorporated in the powde'r mixture prior tosintering.

By incorporating age hardening ingredients such as chromium, nickelsilicide and the like in a copper powder mix, pressing, sintering andthen heat treating to produce age hardening a material of high strengthand hardness is produced. While these materials can be producedsatisfactorily it requires great care in processing, elaborateprecautions for protective atmospheres,

rapid heating and the like. Otherwise a soft shell forms on thematerials during sintering, which must be machined away or the articlediscarded.

Nickel 0.5 to 5 Phosphorus 0.1 to 1 Copper Balance Small percentages ofdiluent ingredients may be present, such as up to 5% cadmium, up to 8%silver and up to 10% of zinc or tin.

It is also contemplated that a reducing agent may be added to the metalpowder mixture to act as a de-oxidizer and provide a protective reducingatmosphere during sintering. This may preferably be a metal hydride,which will evolve nascent hydrogen during sintering. The preferred metalhydride is titanium hydride in proportions ranging from 0.05% to 5% ofthe powder mixture. During sintering nascent hydrogen is given offleaving titanium as an alloying and hardening ingredient in the sinteredbody. Hydrides of other metals of the fourth and fifth group of theperiodic table may be used in the same proportions instead of titaniumhydride, such as:

Zirconium hydride Hafnium hydride Thorium hydride Columbium hydrideTantalum hydride The hydrides of the alkaline and alkaline earth metalsar not as stable as those of the metals of the higher groups of theperiodic table but may be used in like proportions instead of thosepreviously mentioned if proper precautions are taken. They include thefollowing hydrides:

Calcium hydride Barium hydride strontium hydride Sodium hydridePotassium hydride These are quite hygroscopic and decompose rapidly intohydrogen and the corresponding hydroxide when left standing in air atroom temperature.

The hydrides of the fourth group metals titanium, zironium, hafnium andthorium are the most useful. These are stable at room temperature,non-hydroscopic, easy to handle and dissociate gradually duringsintering.

The preferred composition range is:

Per cent Nickel 1.5 to 4 Phosphorus .4 to 1 Copper Balance is sinteredin hydrogen for 1 hour at a temperature between 975 and 1000 C.

It is then usually advisable to repress the sintered blank, aftercooling, in the same die at a higher pressure, such as 40 tons persquare inch.

An age hardening treatment is then applied which may consist in firstheating the body to a temperature of 975 C. to 1000 C. in hydrogen andholding the temperature for hour to effect a solution of the nickel andphosphorus, or nickel phosphide, in the hopper. This is followed byquenching in water or oil and then aging at an elevated temperature suchas 450 C. for several hours, such as 16 hours.

A mixture having the initial composition resulted in a metal body whichhad a hardness of 53 Rockwell B and an electrical conductivity of 40%after aging. No soft skin was formed during sintering. The material wasof good tensile strength and elongation properties.

The material is useful for bearings for internal combustion engines and.other machinery and also for current carrying parts such as the bearingof seam welding rolls.

There are in general three classes of material which may be producedfromcompositions of the present invention depending upon the density towhich the material is pressed. One class has a density, after sintering,repressing and aging of 8 to 8.5 grams per cc. This is a dense nonporousmaterial of high strength, hardness and fatigue strength and is suitablefor heavy duty bearings.

Another class of material has an intermediate desity of between 7.5 and8 gms./cc. and is characterized by the presence of discontinuousporosity together with substantial strength and hardness. This permitssurface absorption of lubricants such as lead, thallium or otherlubricant metals, or of oil or wax.

A third class has a final density of 5 to 7.5 gms./cc. and has acontinuous network of pores so that the entire body may be impregnatedwith a lubricant such as lead, thallium or other metal, or oil or wax.This material is weaker and generally requires a strong backing forsupport. For example the powders may be pressed against a steel back andsintered to it. The first two groups of materials may in some cases beused as a solid bearing or bushing which is pressed into the housing.

In addition to bearings the material may be used for wear resistantmachine parts, valve guides, pressure exerting welding electrodes andelectric contactors.

The phosphorus in these compositions has a cleansing action as well asan alloying action. It serves as a deoxidizer. It also improves theductility and other physical properties of the metal bodies.

While specific embodiments of the invention have been described, it isintended to cover the invention broadly within the spirit and scope ofthe appended claims.

What is claimed is:

1. A bearing formed of a sintered and age hardened metal compositioncontaining 0.5 to 5% nickel, 0.1 to 1% phosphorus, and the balancesubstantially all copper, said composition being characterized byrelatively high strength and hardness and by the absence of a softshell, said soft shell absence being due to the influence of saidphosphorus.

2. A hearing formed of a sintered and age hardened metal compositioncontaining 1.5 to 4% nickel, .4 to 1% phosphorus and the balancesubstantially all copper, the ratio of nickel to phosphorus being about4:1, said bearing being characterized by the absence of a soft shell asthe result of the influence of said phosphorus.

3. A sintered and age hardened metal composition containing 0.5 to 5%"nickel, 0.1 to 1% phosphorus, and the balance substantially all copper,said composition being characterized by relatively high strength and.hardness and by the absence of a soft shell; said soft shell absencebeing due to the influence of said phosphorus.

FRANZ R. HENSEL. EARL I. LARSEN.

